Heat-exchange system

ABSTRACT

A conduit has an inlet portion, an outlet portion, and a main body portion which is to be embedded in a structural element and which is composed of at least two parallel sections having identical internal cross-sectional areas and being in heatexchanging contact with one another over their entire length. One of these sections is adapted to receive fresh incoming heat exchange fluid from the inlet portion and the other section is adapted to receive spent heat-exchange fluid from the first section and to conduct it to the outlet portion. A pump is provided for circulating heat-exchange fluid through the conduit and one or more identical or different heat-exchanges are interposed for adjusting the temperature of the heat-exchange fluid.

United States Patent [1 1 Lohoff HEAT-EXCHANGE SYSTEM [75] Inventor:Hermann Lohoff, Bochum,

Germany [73] Assignee: CTC GmbH, Hamburg, Germany [22] Filed: June 7,1972 [21] App]. No.: 260,389

[30] Foreign Application Priority Data June 8, 1971 Germany P 21 28331.8

[52] US. Cl 62/260, 62/333, 162/515, 165/45, 165/46, 165/49, 165/49,165/168, 165/171 [51] Int. Cl. F25d 23/12 [58] Field of Search 62/260,333; 165/45, 165/46, 49, 168, 171

[56] References Cited UNITED STATES PATENTS 520.930 6/1894 Levey etal... 165/171 2,513,373 7/1950 Sporn 62/260 2,780,415 2/1957 Gay 62/2602,784,945 3/1957 Fodor 165/45 2,996,896 8/1961 Johnson.... 62/2353,012,596 12/1961 Skolout 62/235 [111 3,782,132 [4 1 Jan.l1,1974

Primary Examiner--William J. Wye Att0rney-Michael S. Striker 5 7ABSTRACT A conduit has an inlet portion, an outlet portion, and a mainbody portion which is to be embedded in a structural element and whichis composed of at least two parallel sections having identical internalcrosssectional areas and being in heat-exchanging contact with oneanother over their entire length. One of these sections is adapted toreceive fresh incoming heat exchange fluid from the inlet portion andthe other section is adapted to receive spent heat-exchange fluid fromthe first section and to conduct it to the outlet portion. A pump isprovided for circulating heatexchange fluid through the conduit and oneor more identical or different heat-exchanges are interposed foradjusting the temperature of the heat-exchange fluid.

15 Claims, 3 Drawing Figures PATENTEDJAH 1 1974 3782.132 snmaufz 1HEAT-EXCHANGE SYSTEM BACKGROUND OF THE INVENTION The present inventionrelates generally to heatexchange systems and more particularly to heatexchange systems which are especially suited for use in structuralelements.

In many instances it is necessary to heat or cool enclosed spaces instructures by influencing the temperature of a structural component ofsuch a structure. For instance, it is already known to embed in a panelwhich is installed on or as the floor of a room, a conduit through whichhot or warm water is circulated. This water then yields up heat to thepanel material in which the conduit is embedded, heating the panelmaterial and thus the room in which a surface of the panel is exposed.

The prior art has not previously proposed an arrangement of this type inwhich the temperature at the exposed surface of the panel (which lattercould of course also be provided on or in a wall,or on or in a ceiling),can be varied both uniformly and relatively rapidly. Consequently, theconstructions of this type which are known from the prior art requirerelatively substantial amounts of expended energy for their operation,and do not provide the degree of comfort in a room with which they areassociated, which is desirable.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to overcome these disadvantages of the prior art.

More particularly, it is an object of the present invention to providean improved heat-exchange system which overcomes such disadvantages.

Still more particularly, it is an object of the invention to providesuch an improved heat-exchange system which utilizes one or moreconduits that can be embedded in part in a structural element and will,when the heat-exchange system is operated, provide for a uniformtemperature over the entire exposed surface of the structural element.

In pursuance of these objects and of others which will become apparenthereafter, one feature of the invention resides in a heat-exchangesystem which, briefly stated, comprises a combination of conduit meansincluding an inlet portion, an outlet portion and a main body portion,intermediate the inlet and outlet portions. The main body portion isadapted for embedding in a structural element and includes at least twoparallel sections of at least substantially identical crosssectionalarea and which are in heat-exchanging contact with one another, over atleast substantially their entire length. One of these conduit sectionsis adapted to receive incoming fresh heat-exchange fluid from the inletportion and the other conduit section is adapted to receive spentheat-exchange fluid from the first section and to conduit it to theoutlet section. Circulating means is provided for circulatingheatexchange fluid through the conduit means and heatexchange means isprovided for adjusting the temperature of the heat-exchange fluidcirculated by the circulating means to the desired level.

Due to the fact that according to the invention the aforementionedconduit sections extend in parallel, have substantially identicalcross-sectional areas and are in heat-exchanging contact with oneanother over at least substantially their entire length, the temperaturegiven a structural element in which they are embedded, and in particularat the exposed surface of such a structural element, is highly uniformeverywhere. Because of this, the comfort of persons in a room in whichsuch a structural element is used for heating or cooling purposes issubstantially improved, and, a concomitant not to be overlooked, theenergy required to be expended in order to obtain the desiredtemperature level can be reduced over what is known from the prior art.

If the heat-exchange system of the present invention is to be utilizedfor cooling the structural element in which its conduit sections areembedded, then cooling fluid must of course be passed through theconduit means. In such a case it is, however, essential to assure thatthe surface temperature of the structural element being cooled will,depending upon the ambient conditions in the air of the room in which itis used, not fall below that temperature at which the water vaporcontained in the ambient air will begin to condense at the exposedsurface.

The concept of embedding conduits for instance in a floor of astructure, and circulating cooling water through them is not in itselfnovel. It is for instance known to circulate town water or well waterthrough such conduits, water which in temperate zones usually has atemperature of substantially 8 14 C. If the water temperature is forinstance 14 C. and the resulting surface temperature of the floor is 17C, the dew point temperature (the temperature at which water vapor inthe air of a room whose floor is being cooled thusly, will condense) isnot met on many days throughout the year. In other words, the surfacetemperature of the floor will be cooler than the dew point temperatureand as a result condensation will take place. To prevent this it isnecessary in such case to shut off the system and do without coolingentirely, or to either heat the incoming town or well water or mix itwith warm water in order to raise its temperature and thereby thesurface temperature of the floor. Evidently, the former possibility isuncomfortable and the latter possibility is expensive.

A further disadvantage of this prior art approach to cooling is the factthat the floor can be cooled only highly unevenly, that is there will belocal areas where the floor is cooler than at other areas. Aside fromthe undesirable influence on the comfort of users of the room, thisfurther causes the development of stress cracks in the floor.

The present invention, however, eliminates all these problems becausedue to the fact that the conduit sections which respectively carry theincoming fresh heatexchange fluid and the outgoing spent heat-exchangefluid, extend in parallelism and are in contact over all orsubstantially their entire length, with the heatexchange fluid flowingin opposite directions in the respective conduit sections, a uniformheating or cooling of the structural element in which the conduitsections are embedded is assured. Furthermore it has been found thatwhen the heat-exchange system according to the present invention itutilized for cooling purposes, the incoming cooling fluid (usuallywater) can have a temperature which is actually below the previouscritical temperature (at which the structural element was cooled to thepoint where condensation would take place at its exposed surface)without causing condensation. Evidently, this increases theeffectiveness of the system.

It is advantageous to provide a heat exchange unit, which according toone concept of the invention may be in form of a conduit coil which isembedded in the soil, and connected with the inlet portion of theconduit means so that the cooling fluid will pass through this conduitcoil. The latter should advantageously be of synthetic plastic materialto avoid rusting.

The heat-exchange unit can, however, also be in form ofa cooling coilwhich is interposed in the inlet portion of the conduit means, althoughthis second possibility, contrary to the first-mentioned one whichrequires no additional operating expenses, does require additionalexpenses for its operation. On the other hand, the second possibilityhas been found to be highly advantageous where high cooling capacity isrequired, especially in view of the fact that at an ambient airtemperature of 32 C. and a relative humidity of 40 percent such coolingtower can still produce a cooling water temperature of 21 C.

However, the heat exchange unit can also be in form of a heat pump, ormore particularly the evaporator of the heat pump whose condenser isconstructed as a conduit coil which may be embedded in the soil andwhich also advantageously is of synthetic plastic material. With such aconstruction it is possible to select heating or cooling at the choiceof a user, simply by switching the heat pump from cooling operation toheating operation. Such an arrangement is particularly advantageousbecause of the low energy requirement and expenses which are merelyneeded for operating the compressor, whereas the cooling or heatingenergy is taken directly from the soil.

A heat pump is so well known in its construction and its operation, thata detailed discussion is not thought to be necessary herein. However, ifadditional information is required, reference may be had to Heating andVentilating Engineering Databook", Clifford Strock, published by TheIndustrial Press, N. Y. 1938, Section I0.

I have found it to be particularly advantageous if the inner diameter ofthe flow passages in the conduit means is at most 25 mm., and if, shouldthe main body portion have more than one conduit sections for freshheat-exchange fluid and more than one conduit section for spentheat-exchange fluid, the distance between adjacent conduit sections forfresh heat exchange fluid (and again the distance between adjacentconduit sections for spent heat exchange fluid), is not substantiallygreater than l8 cm.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic illustrationof a heatexchange system in accordance with the present invention;

FIG. 2 is a diagrammatic illustration showing a further heat-exchangesystem according to the invention; and

FIG. 3 is a Mollier diagram for humid air.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 I have illustrated astructural element 2, for instance a panel or plate, which is intendedto constitute the exposed floor of a room (not shown). Such panel orplate may be cast of a hardenable material, for instance a synthetic asshown, concrete or other material, and embeds in it the main bodyportion of a conduit having an inlet portion 1 and an outlet portion 1".The embedded body portion of the conduit 1 has at least two sections,one being identified with reference numeral la and carrying the incomingheat-exchange fluid which enters through the conduit portion 1, whereasthe other is identified with reference numeral lb and carries the spentheat exchange fluid which it receives from the section 10 and passes onto the outlet portion 1". For better identification, the section 1a isshown in broken lines and the section lb in solid lines. It will be seenthat the sections 1a and lb are here shown in form of severalconvolutions, and that the number of convolutions may be greater orsmaller than what has been illustrated. If each section 1a (andsimilarly lb) has two or more parallel subdivisions due to the presenceof two or more convolutions, then these subdivisions of the same sectionshould be advantageously spaced no more than the distance I apart fromone another. with this distance not substantially exceeding 18 cm. It isadvantageous if the sections 1a and lb are deposited on a somewhatdiagrammatically illustrated steel reinforcing mesh 2' to which they aresecured and together with which they are embedded in the material of thestructural element 2.

Reference numeral 3 in FIG. 1 identifies a support, for instance afoundation of concrete or the like on which the element 2 is positioned.Interposed between the support 3 and the element 2 is an intermediatecomponent 2" (which may be composed of a plurality of layers) forthermal insulating purposes, accoustical insulating purposes, andvapor-barrier purposes. The provision of the component 2" is known inthe art and conventional.

The inlet portion 1' and the outlet portion 1" are connected viarespective collecting receptacles 1" and 1" with a boiler 4 which in theillustrated embodiment is provided with a closed expansion vessel 4' anda safety valve 4". A pump 5 for cooling water is interposed in the inletportion 1, together with a three-way mixing valve 6, which is connectedvia a branch conduit 6' with the outlet portion 1".

I have chosen to illustrate in FIG. 1 four different possibilities ofproviding a heat-exchange means for adjusting the temperature of thewater to be passed through the conduit 1 to a desired level. It shouldbe understood that each of the heat-exchange means, which are identifiedwith reference numerals 7, 8, 9 and 20, can be used individually or inany combination with any or all of the others. In other words, it ispossible to use all four illustrated heat-exchange means in a singlesystem, or to use any one of them individually or to use two or more ofthem in any desired combination.

Discussing firstly the means identified with reference numeral 7, itwill be seen that this utilizes a conduit coil 7a (preferably ofsynthetic plastic material to avoid rusting) which is embedded in thesoil 7 and is connected with the inlet portion 1 of the conduit 1 via afirst conduit connection 7" and a second conduit connection 7".interposed between the locations where the conduit connections 7 and 7"communicate with the conduit portion 1 is a valve 11 which is providedin the conduit portion 1'. interposed in the conduit connection 7" is avalve and interposed in the conduit connection 7" is a valve 10.

If the temperature of the water to be supplied to the sections la and lbis to be influenced with this heatexchange arrangement, then the valve11 is closed, and the valves 10 and 10' are opened. Water circulated bythe pump 5 now enters the connection 7" via the valve 10, passes throughconduit coil 7a in which it is cooledv due to the coolness of thesurrounding soil 7', and returns via the conduit connection 7' and thevalve 7 downstream of the valve 11, into the inlet portion 1' from whereit circulates first through the conduit section la and then the section1b to return into the outlet portion 1. By the time the water reachesthe conduit portion 1" it has of course warmed up, having absorbed heatfrom the material of the structural element 2. ltpasses now via thecollecting receptacle 1" and the branch conduit 6' and valve 6 back intothe pump 5 to begin its circulation anew. This particular arrangement isadvantageous insofar as it requires no additional operating expenses,forinstance energy to operate a fan or the like, and in thatparticularly if the conduit coil 7a is of synthetic plastic material theinstallation is largely corrosion resistant and requires no maintenance.

The second heat exchange arrangement is identified with referencenumeral 8,making use of the illustrated cooling tower which may be ofany construction well known per se to those skilled in the art and whichtherefore requires no detailed discussion. The cooling tower isconnected via the conduit connection 8 and the valve 8' with the conduitportion 1' upstream of a valve 12 interposed in the latter; the coolingtower is further connected with the conduit portion 1 downstream of thevalve 12 via a conduit connection 8" and a valve 8". In this case, it isdesirable to have the pump for the coolingwater located in the conduitportion 1 downstream of the juncture of the latter with the conduitconnection 8", as indicated at 5'. When the valve 12 is closed the pump5' draws cooling water via valve 8', conduit connection 8' through thecooling tower 8, and subsequently via the conduit connection 8" and thevalve 8 into the conduit portion 1 to circulate it through the conduit 1in the manner discussed previously. This arrangement has the particularadvantage that the cooling capacity of the cooling tower can beprecisely accommodated to the maximum cooling requirements anticipated,and that it is possible to cool the incoming fresh cooling water to atemperature of 2l C. when the ambient air has a temperature of 32 C. anda-relative humidity of 40 percent. For this reason, this second heatexchange arrangement is particularly advantageous where hotels, officebuildings or the like are to be cooled with a heat-exchange systemaccording to the present invention.

A third heat-exchange arrangement is identified with reference numeral9, utilizing the diagrammatically illustrated heat pump which has beenpreviously discussed. Essentially this arrangement provides anevaporator 9' interposed in the conduit portion 1' so that it canexchange heat with the cooling water passing through the latter, acompressor 9", a condenser 9" and a pressure reducing valve 9". Heat iswithdrawn from the cooling water passing through the evaporator 9 by thecooling medium of the heat pump. This cooling medium evaporates and thevapor is drawn off the evaporator 9' by the compressor 9" and compressedto such an extent that it reaches an appropriate temperature. Thecompressed vapor is then supplied to the condenser 9" whose coolingsurface area is of requisite size, and it is cooled by thediagrammatically illustrated blower. When it has been cooled it is thenreturned via the pressure reducing valve 9 as cooling medium condensateinto the evaporator 9 where the cycle begins again.

Reference should be had in this connection to the embodimentillustratedin FIG. 2, where a particularly advantageous version of the novelheat-exchange system is illustrated, using the third heat-exchangearrangementof FIG. 1, or rather a somewhat different embodiment thereof.FIG. 2, wherein like reference numerals identify the same components asin FIG. 1, provides a heat pump in which the condenser 9" of thearrangement of FIG. 1 is replaced by a conduit coil 9" which is eitherembedded in the soil or is immersed in well water, in the water of astream or the like. In other words, the requirement for supplying energycapable of operating the diagrammatically illustrated blower of thecondenser in FIG. 1 has been eliminated.

interposed between the evaporator 9' in FIG. 2 and the compressor 9"there is provided a four-way valve 15,and two pressure reducing valves13 and 14 are interposed between the conduit coil 9" and the evaporator9. Valves l3, 13', 14 and 14" are provided, permitting either thereducing valve 13 or 14 to operate independently of the other.

With this arrangement, it is possible to both heat and cool via thenovel heat-exchange system. If cooling is desired, then the heat pumpacts as a refrigerator and the cooling medium therein flows through itin the direction indicated by the flow-line arrows. The device 9' actsas an evaporator and the conduit coil 9" acts as the condenser.

The same arrangement can, however, also serve to provide heating of thefluid circulating through the conduit 1. Thus, it can replace the boiler4 which in the embodiment of FIG. 1 is provided to be able to use thesystem when it is desired to heat rather than cool the structuralelement 2. In the embodiment of FIG. 2, however, the heat pump itselfcan act to heat the cooling fluid, for which purpose it is merelynecessary to operate the four-way valve 15 so that the direction offluid circulating in the heat pump is now as indicated by thebroken-line arrows of FIG. 2. In this case, the conduit coil 9" acts asthe evaporator and the unit 9' acts as the condenser, meaning that heatis withdrawn from the soil in which the conduit coil 9 is embedded (orthe water in which it is located), raised to a high temperature via theoperation of the compressor 9" and then transmitted via the element 9'to the water circulating through the conduit portion 1' inheatexchanging engagement with the element 9. Because the surfacetemperature of the structural element 2 shown in FIG. 1 must not exceeda temperature of approximately 27-28 C., not only to provide a highdegree of comfort for persons present in an enclosure in which theelement 2 is provided but also in order to avoid the formation of stresscracks in the element 2, the water temperature in the incoming watercirculating in the conduit portion 1 can be relatively low, because ofthis the heat-exchange system has a high efficiency both when the systemof FIG. 2 is operated for cooling and when it is operated for heatingpurposes.

Returning to FIG. 1, it will be recalled that there is still a fourthheat-exchange arrangement illustrated in this Figure. This is identifiedwith reference numeral 20, utilizing a receptacle preferably ofsynthetic plastic material. A conduit coil 20' is located in thereceptacle 20 and connected with the conduit portion 1' so that when thevalve 22 in the conduit portion 1 is closed and the mixer valve 22 isopened, the water passing through the conduit portion 1 will circulatethrough the conduit coil 20" under the influence of the pump 5.

A pump 23 is provided, for instance a submersible pump, which is locatedin the soil at an appropriate depth, such as to be able to withdrawgroundwater, and this groundwater is then circulated via the pipe orconduit 23 into the receptacle 20 from where it is returned via the pipeor conduit 23 back to the groundwater. The return takes place at asufficient distance from the intake of the pump 23 so that the latterwill not draw in the warmer spent water which is being returned via theconduit or pipe 23. Of course, it is possible to discharge the waterfrom the receptacle 20' to a point other than back to the groundwaterbut by so doing as shown in FIG. I, the groundwater level will not bedropped.

In this embodiment it will be appreciated that heat is exchanged betweenthe groundwater circulating through the receptacle 20 and the coolingwater circulating through the conduit coil 20, thereby cooling thecooling water which is then returned into the conduit portion 1' andcirculates through the sections la and lb. This particular possibilityhas the advantage that the receptacle 20 can be positioned so as to bereadily accessible, and that it as well as the conduit coil 20' are notsubjected to any significant danger of mechanical damage and can also bereadily cleaned if and when necessary. Furthermore, the mixing valve 22makes possible an admixture of the warmer water in the incomingconnection of the coil 20" with the cooler water which has been cooledin the receptacle 20', so that the temperature of the water whichreaches the sections la and lb can be particularly easily regulated.

Coming, finally to FIG. 3, it will be seen that this is aMollier-diagram wherein the advantages of the present invention areclearly evident. The curve a shown in the diagram is representative ofthe ambient air conditions which prevail in moderate climates on anaverage summer day. Given the conditions as set forth by the curve a andassuming that a room utilizing a structural element providing with theheat-exchange system according to the present invention receives freshair, the ambient air in the room at the point A (see FIG. 3) would havea temperature of 32 C., 40 percent relative humidity and a dew pointtemperature of about l6,8C. In other words, the dew point temperature isthat temperature below which the water contained in the air willcondense on the surface of the element 2. Thus, it follows that thesurface of the element 2 of FIG. I must not reach or drop below the dewpoint temperature of l6.8C. in the example. Quite surprisingly, however,I have found that with my novel heat-exchange system the temperature ofthe incoming cooling water, that is the cooling water which is suppliedvia the conduit portion 1 may actually be below the dew point, becausedue to the counterflow of water in the conduit sections 1a and lb (whichare in heat-exchanging contact with one another), the temperature in theimmediate vicinity of the sections la and 1b will still be above the dewpoint temperature (assuming that the temperature of the incoming waterin the conduit portion 1 is not too far below the dew point temperature)This is true even if the room in which such a structural element is usedreceives fresh air directly from the exterior, that is ambient freshair.

On the other hand, if the structural element is used in a room whereprovisions are made for dehumidifying the air, a temperature of theincoming cooling water in the conduit portion 1 of C. to C. and evenslightly below is permissible, depending upon the condition of the airin the room, for instance at 25 C. and between 50-60 percent relativehumidity, without having to anticipate that the exposed surface of theelement 2 would reach the critical dew point temperature at whichcondensation could take place. This is graphically shown by the curve bin FIG. 3.

The present invention has other advantages beyond those which havealready been pointed out. One of these is, for instance, the fact thatthe room temperature which is comfortable in a room whose temperature isbeing regulated with the heat-exchange system according to the presentinvention, can be higher than the temperature which is consideredcomfortable if one or the other of the air-conditioning systems knownfrom the prior art is employed. This means, that the heatexchange systemaccording to the present invention is capable of providing for acomfortable room temperature without requiring a dehumidifying systemfor the air in the room, and even at maximum cooling capacity at summertime, the critical surface temperature of the element 2 is reached if atall only on a very few days of the year. For instance it has been foundthat if the temperature of the incoming water in the portion 1 is 20C.resulting in a surface temperature of the element 2 of approximately2324 C., a room provided with the element 2 could be maintained at acomfortable room temperature of 2728 C.

If the heat-exchange system according to the present invention is to beused in large installations, for instance for cooling large buildings orother structures, it is advisable to connect a plurality of conduits inparallel with one another, as is indicated in FIG. 1 by the two conduitportions 1, 1" and conduit portions 21', 21" of a second conduit. Thispermits the cooling of individual zones in such a structure toindividual temperatures (and of course, the heating thereof, if desired)in dependence upon particular requirements, for instance the North,South, East or West exposure of a particular area of the structure.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in aheat-exchange system, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can,

by applying current knowledge, readily adapt it for various applicationswithout omitting features that, from the standpoint of prior art, fairlyconstitute essential characteristics of the generic or specific aspectsof this invention and, therefore, such adaptations should and areintended to be comprehended within the meaning and range of equivalenceof the following claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

l claim:

1. In a heat-exchange system, in combination, conduit means including afluid inlet portion, a fluid outlet portion, and a main body portionadapted for embedding in a structural element, said main body portionincluding a first section having a first upstream end which communicateswith said inlet portion and also having a first downstream end, and asecond section extending along said first section and contacting thesame in heatexchange surfact-to-surface contact over substantially theentire length thereof, said second section having a second upstream endcommunicating with said first downstream end and also having a seconddownstream end communicating with said outlet portion; circulating meansfor circulating heat-exchange fluid through said conduit means so thatthe fluid flows initially in one direction through said first section,and thereupon in counter-flow to said one direction through said secondsection; and heat-exchange means for adjusting the temperature of saidheat-exchange fluid to a desired level.

2. In a system as defined in claim 1, wherein said circulating means isoperative for circulating a cooling fluid through said conduit means.

3. In a system as defined in claim 1, wherein said heat-exchange meansis interposed in said inlet portion of said conduit means.

4. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a conduit coil adapted to be embedded in soil and connected incircuit with said inlet portion so that heat-exchange fluid circulatesthrough said conduit coil.

5. In a system as defined in claim 4, wherein said conduit coil is ofsynthetic plastic material.

6. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a cooling tower interposed in said inlet portion.

7. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a heat pump including an evaporator and a condenseroperatively associated with said evaporator and constituted by a conduitcoil adapted to be embedded in soil.

8. In a system as defined in claim 7, wherein said conduit coil is ofsynthetic plastic material.

9. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a heat pump operable for selective heating or cooling of saidheat-exchange fluid at the will of a user.

10. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a receptacle, a conduit coil located in said receptacle andconnected in circuit with said inlet portion so that said heat-exchangefluid flows through said conduit coil, and supply means for passing aflow of cooling water through said receptacle in contact with saidconduit coil.

11. In a system as defined in claim 10, wherein said receptacle is ofsynthetic plastic material.

12. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a heat pump including an evaporator, and a condenseroperatively associated with said evaporator and exposed to a stream ofair.

13. In a system as defined in claim 1, wherein at least said conduitsections have an inner diameter of at most 25 mm.

14. In a system as defined in claim 1; further comprising additionalconduit means parallelling the firstmentioned conduit means and alsooperatively associated with said circulating means and said heatexchangemeans.

15. In a system as defined in claim 13, wherein said sections eachcomprise at least a first portion and at least one second portion; andwherein said first portions are transversely spaced from one another bya distance not exceeding substantially 18 cm, and said second portionsare also transversely spaced from one another by a distance notexceeding substantially 18 cm. l

1. In a heat-exchange system, in combination, conduit means including afluid inlet portion, a fluid outlet portion, and a main body portionadapted for embedding in a structural element, said main body portionincluding a first section having a first upstream end which communicateswith said inlet portion and also having a first downstream end, and asecond section extending along said first section and contacting thesame in heat-exchange surfact-to-surface contact over substantially theentire length thereof, said second section having a second upstream endcommunicating with said first downstream end and also having a seconddownstream end communicating with said outlet portion; circulating meansfor circulating heat-exchange fluid through said conduit means so thatthe fluid flows initially in one direction through said first section,and thereupon in counterflow to said one direction through said secondsection; and heatexchange means for adjusting the temperature of saidheatexchange fluid to a desired level.
 2. In a system as defined inclaim 1, wherein said circulating means is operative for circulating acooling fluid through said conduit means.
 3. In a system as defined inclaim 1, wherein said heat-exchange means is interposed in said inletportion of said conduit means.
 4. In a system as defined in claim 3,wherein said heat-exchange means comprises a conduit coil adapted to beembedded in soil and connected in circuit with said inlet portion sothat heat-exchange fluid circulates through said conduit coil.
 5. In asystem as defined in claim 4, wherein said conduit coil is of syntheticplastic material.
 6. In a system as defined in claim 3, wherein saidheat-exchange means comprises a cooling tower interposed in said inletportion.
 7. In a system as defined in claim 3, wherein saidheat-exchange means comprises a heat pump including an evaporator and acondenser operatively associated with said evaporator and constituted bya conduit coil adapted to be embedded in soil.
 8. In a system as definedin claim 7, wherein said conduit coil is of synthetic plastic material.9. In a system as defined in claim 3, wherein said heat-exchange meanscomprises a heat pump operable for selective heating or cooling of saidheat-exchange fluid at the will of a user.
 10. In a system as defined inclaim 3, wherein said heat-exchange means comprises a receptacle, aconduit coil located in said receptacle and connected in circuit withsaid inlet portion so that said heat-exchange fluid flows through saidconduit coil, and supply means for passing a flow of cooling waterthrough said receptacle in contact with said conduit coil.
 11. In asystem as defined in claim 10, wherein said receptacle is of syntheticplastic material.
 12. In a system as defined in claim 3, wherein saidheat-exchange means comprises a heat pump including an evaporator, and acondenser operatively associated with said evaporator and exposed to astream of air.
 13. In a system as defined in claim 1, wherein at leastsaid conduit sections have an inner diameter of at most 25 mm.
 14. In asystem as defined in claim 1; further comprising additional conduitmeans parallelling the first-mentioned conduit means and alsooperatively associated with said circulating means and saidheat-exchange means.
 15. In a system as defined in claim 13, whereinsaid sections each comprise at least a first portion and at least onesecond portion; and wherein said first portions are transversely spacedfrom one another by a distance not exceeding substantially 18 cm, andsaid second portions are also transversely spaced from one another by adistance not exceeding substantially 18 cm.